Changes

Another category of mash tun in use by the homebrewer is the converted keg. Typically the top is cut off a large stainless steel keg producing a mash tun that is 15 gallons or more in size. The mash tun is then often insulated with foam, fitted with a metal false bottom and spigot, and then either a burner is used to maintain temperature or the whole tun is covered and insulated to make a very large cooler. Given the volume of these kegs, typically more advanced brewers use these systems.

If you have a controlled heat source, you can also make a mash tun from any pot large enough to hold the mash. In this case you just raise the heat on the pot, stirring as you go, until you reach your target temperature. Now you turn the heat down to maintain that temperature. The challenge is that it is difficult to maintain a steady temperature for a long time with a pot on a stove. However, commercial brewers who have temperature control systems do successfully use heated mash tuns to mash.